WO2008062406A2

WO2008062406A2 - Continuously variable transmission-based planetary gear

Info

Publication number: WO2008062406A2
Application number: PCT/IL2007/001429
Authority: WO
Inventors: Josef Yanay
Original assignee: Josef Yanay
Priority date: 2006-11-20
Filing date: 2007-11-20
Publication date: 2008-05-29
Also published as: EP2097659A4; WO2008062406A3; US20090227413A1; US8152673B2; JP2010510452A; EP2097659A2; CA2668977A1

Abstract

A continuous variable transmission is provided that is based on gearwheels. The novel gear acts as an efficient transmission that can replace conventional manually or automatics gears. The CVT comprises sun gear connected to input shaft and ring gear fixedly connected to output shaft. Planet gear is arranged between and engaged with the sun gear and the ring gear wherein a planet carrier that is vertically enclosing the ring gear and the sun gear is provided with a canal in which an oil pump is provided. A control valve is capable of controlling the flow of lubricant within the canal.

Description

CONTINUOUSLY VARIABLE TRANSMISSION-BASED

PLANETARY GEAR

FIELD OF THE INVENTION

The present invention relates to continuously variable transmission (CVT). More particularly, the present invention relates to a planetary gear for CVT.

BACKGROUND OF THE INVENTION

Continuous variable transmission (CVT) is a user and environmentally friendly automatic type transmission that can be used in different industries as well as in transportation. In vehicles, the control unit as a separated unit connected here which is responsible to the gear ratio changing, causing transmission automatically selects the gear ratio that is the exact ratio needed to the road speed in which the car is driven in. Basically, the purpose of CVT is to continuously vary the transmission ratio. The idea of CVT is known for years; however, to date, its implementation especially in vehicles had faced different problems.

Three types of CVT were developed; the friction CVT, which vary the radius of the contact point between two rotating objects and this is the tangential velocity; the hydrostatic CVT that vary the fluid flow with variable displacement pumps into hydrostatic motors; and ratcheting CVT that vary the stroke of the reciprocating motion that is connected to a free wheel resulting in an unidirectional rotation. Each mechanical system has its own inherent limitations. At the early decades of the 20century, one concept of the continuous transmission was developed by H. van Doorne. Experimental version was built in a Lloyd LP400 in the fifty's and eventually the first cars were ordered and produced by the DAF company. Although the technology of CVT actually dates back decades, these types of transmissions did not penetrate the car industry and has until recently been limited mostly to smaller cars with transversely-mounted engines and front wheel drive. Only in the recent years, there are attempts to drive the CVT into the mainstream of the automobile industry.

Other transmissions were developed and another example is the CLAAS¹ CVT. Primary components of the HM transmission of CLAAS are a reverse unit, hydrostatic unit, double planetary gear and low and high speed coupler shafts, and a multistep reduction gear downstream of the coupler shaft. The power is split in the reverse unit into mechanical and hydro static paths.

Audi's engineers developed a multitronic CVT for years and now stating that the multitronic finally overcomes all the drawbacks of the stepless principles. This CVT is an improvement of the van doorne CVT type based on chain V-belt principle. A key element of the multitronic is a variator that adopts a new transmission element called a link-plate chain made entirely from steel and is almost as flexible as V-belt so to handle high forces and torque levels of the A6's engine. However, after few years of employing the multitronic in Audi cars, reports from customers show that after a certain amount of mileage, the multitronic is experiencing failure.

It appears that other CVT transmissions are also experiencing failure after a certain mileage. It is therefore a long felt need to develop a CVT that inherently have the potential benefits of the CVT transmission and can work for a long time without or with minimal failure. There is a need for an efficient transmission that will be able to replace the conventional manually or automatics gears that are operated using steps in the gear ratio. SUMMARY OF THE INVENTION

It is an object of the present invention to provide a CVT that is not friction based and is working on the base of gearwheels. It is another object of the present invention to provide a gear for a CVT that is adapted to transmit force and torque without experiencing breakage.

It is yet another object of the present invention to provide a gear that acts as an efficient transmission and can replace the conventional manually or automatics gears. It is provided in accordance with a preferred embodiment of the present invention a continuously variable transmission comprising a sun gear connected to an input shaft; a ring gear fixedly connected to an output shaft; at least one mating pair planet gear arranged between and engaged with said sun gear and said ring gear; a planet carrier, adjacent to and vertically enclosing said ring gear and said sun gear through which said input shaft passes, is provided with a canal; at least one control valve adapted to control flow of lubricant within said canal; at least one oil pump provided in said canal and engaged with said at least one planet gear that is capable of rotating together with said planet gear so as to allow flow of the lubricant within said canal. It is further provided in accordance with another preferred embodiment of the present invention, one mating pair of planet gear is provided.

It is further provided in accordance with another preferred embodiment of the present invention, said at least one oil pump is a pair of mating gears.

It is further provided in accordance with another preferred embodiment of the present invention, a joined shaft is connecting one of said pair of planet gears to one of said pair of mating gears. It is further provided in accordance with another preferred embodiment of the present invention, said canal is circular.

It is further provided in accordance with another preferred embodiment of the present invention, the number of control valves equals the number of oil pumps.

It is further provided in accordance with another preferred embodiment of the present invention, three control valves are associating with three oil pumps.

It is further provided in accordance with another preferred embodiment of the present invention, said at least one oil pumps comprises an outer rotor provided with peripheral ridges and an inner rotor provided with corresponding peripheral protrusions and wherein the rotation of the inner rotor and the outer rotor pushes oil that is disposed between them.

It is further provided in accordance with another preferred embodiment of the present invention, said input shaft is rotated by a power source.

It is further provided in accordance with another preferred embodiment of the present invention, said sun gear is provided with a bore that is in connection with said input shaft.

It is further provided in accordance with another preferred embodiment of the present invention, said at least one control valve is operated by means selected from a group of mechanical, electrical, hydraulic, or pneumatic mechanism, etc.

It is further provided in accordance with another preferred embodiment of the present invention, when said at least one control valve is fully closed and oil is not flowing in said canal, said sun gear, said planet gear, said ring gear and said oil pump are fixed together as a unit with said planet carrier causing the continuous variable transmission to rotate together so as to establish a transmission gear ratio of 1 to 1.

It is further provided in accordance with another preferred embodiment of the present invention, the continuous variable transmission is associated with a clutch roller. It is further provided in accordance with another preferred embodiment of the present invention, the CVT is further associated with a slider provided with a movable wedge roller capable of associating with said planet carrier and stopping said planet carrier from rotation. It is further provided in accordance with another preferred embodiment of the present invention, said wedge roller stops said planet carrier by friction.

It is further provided in accordance with another preferred embodiment of the present invention, said slider is a disc mounted onto a fixed axle wherein said disc is capable of moving in a limited angular movement between a first position and a second position onto said fixed axle and wherein in the first position said wedge roller is loose and in the second position said wedge roller is pressing a gear that associates with an external ring gearwheel and force said planet carrier to stop its rotation backward.

It is further provided in accordance with another preferred embodiment of the present invention, said axle is provided with a key projection and said disc is provided with a corresponding keyway that is limited within said key projection to allow said first position and said second position.

It is further provided in accordance with another preferred embodiment of the present invention, said wedge roller is provided within a recess between a gearwheel that is associated with said planet carrier and said disc.

BRIEF DESCRIPTION OF THE FIGURES

In order to better understand the present invention and appreciate its practical applications, the following Figures are attached and referenced herein. Like components are denoted by like reference numerals.

It should be noted that the figures are given as examples and preferred embodiments only and in no way limit the scope of the present invention as defined in the appending Description and Claims. Figure 1 illustrates an exploded view of continuously variable transmission apparatus gears in accordance with a preferred embodiment of the present invention.

Figure 2 illustrates a partial cross sectional view of continuously variable transmission in accordance with a preferred embodiment of the present invention.

Figure 3 schematically illustrates an oil pump that is used within the oil canal shown in Figure 1.

Figure 4 illustrates a cross sectional view of a planet carrier in accordance with another preferred embodiment of the present invention, provided with three oil pumps.

Figure 5 illustrates an oil pump that can be utilized in a CVT in accordance with another preferred embodiment of the present invention.

Figures 6A, B schematically illustrate a roller clutch working on the principle of a CVT in accordance with a preferred embodiment of the present invention, in driving and floating situations, respectively.

Figures 7A, B illustrate a roller clutch working on the principle schematically shown in Figure 6.

DETAILED DESCRIPTION OF THE INEVNTION AND FIGURES

The present invention provides a novel and unique CVT that is rendered with numerous advantages relative to existing traditional transmissions. Among the advantages especially in vehicles there are the constant and stepless acceleration, the engine is working on optimal power range regardless the speed, better response to changes in road conditions, less power loss, and more. The mechanical version of the CVT deals with either frictional based CVT - the pulleys and V-belt CVT or the toroidal CVT that works by varying the radius of the contact point between two rotating objects. The mechanism of the CVT of the present invention does not involve friction, but is hydraulic; it uses pump or pumps to vary the hydraulic fluid flow. The hydraulic flange - planet carrier combined with planetary gearset to form a hybrid system.

The CVT of the present invention is advantageous in the fact that the gear ratio can change rapidly. This behavior is unachievable in the tools that are provided in the vehicle industry of today.

According to one aspect of a CVT of the present invention, the continuously variable transmission comprises a sun gear connected to an input shaft, a ring gear fixedly connected to an output shaft and at least one planet gear arranged between and engaged with the sun gear and the ring gear. A planet carrier that partially encloses and is positioned adjacent to the ring gear is provided with a canal in which lubricant is received. A control valve is adapted to control the flow of the lubricant within the canal in the planet carrier. Oil pump engaged with the planet gear and adapted to rotate together with the oil pump that is provided so as to push and compress alternately the flow of lubricant within the canal.

Reference is now made to Figure 1 illustrating an exploded view of continuously variable transmission apparatus in accordance with a preferred embodiment of the present invention. Continuously variable transmission 10 comprises a sun gear 12, planet gear 14 preferably comprised of a pair of gears, and a ring gear 16. Basically, input shaft 18 is connected to sun gear 12 through a floating bore in the planet carrier and oil canal cover and an output shaft 20 is fixedly connected to ring gear 16. Input shaft 18 that is adapted to rotate due to power source such as an engine to which it may be connected, forces sun gear 12 to rotate. Sun gear 12 is coupled with planet gears 14 that rotate as well as a consequence of the sun gear rotation. The planet gears are coupled also with ring gear 16 that in turn rotates output shaft 20, which is fixedly connected to the ring gear.

It should be noticed that the planet gears can be made of gearwheels having different diameters without limiting the scope of the present invention.

The gears are adjacent to a planet carrier 22 that is enclosing the ring gear by its diameter and enclosing the sun gear and the planet gear, which is disposed between the sun gear and the ring gear. The input shaft passes through a hole substantially in the middle of planet carrier 22. Planet carrier 22 is provided with substantially circular oil canal 24 adapted to receive a lubricant and allowing a lubricant to flow within the canal. The flow of the lubricant within oil canal 24 is controlled by a control valve 26 while an oil pump 28 is provided within the canal. The control valve can be operated in several optional manners such as mechanically, electrically, hydraulically, pneumatically or any other way without limiting the scope of the present invention.

One of the pair of the planet gear acts as an oil pump drive gear 29 that is provided with a joined shaft 30 that is engaged also with oil pump 28. When planet gear 14 is rotating, oil pump drive gear 29 constantly rotates oil pump 28 causing the lubricant within the canal to flow.

It should be mentioned that the oil pump and the planet gear can be associated in a direct and indirect manner. In the direct manner, a joint shaft can be used as shown herein; however, any other indirect association can be used. Reference is now made to Figure 2 illustrating a partial cross sectional view of continuously variable transmission in accordance with a preferred embodiment of the present invention. Sun gear 12 is shown to substantially be positioned in the same plane as ring gear 16 and planet carrier 22 is shown to enclose CVT 10. Shaft 30 is clearly shown to be in engagement relationship with oil pump drive gear 29, which is one of pair of planet gear 14 and rotates with it, as well as with oil pump 28. Reference is now made to Figure 3 schematically illustrating an oil pump that is used within the oil canal shown in Figure 1. Oil pump 28 comprises two mating gears wherein one of the pair is engaged through a shaft to a planet gear as shown and explained herein before. Optionally, the mating gears of the oil pump are engaged through a shaft by gearwheel or gearwheels set to the oil pump in order to drive gear 28.

Optionally, other driving means can be employed to drive the oil pump without limiting the scope of the present invention.

Oil pump 28 is provided within oil canal 24 in which lubricant 25 is received. The rotation of both gears 28 causes lubricant 25 to flow within oil canal 24 in the direction shown by the arrows. However, it should be emphasized that more than a pair of mating gears can be used and moreover, other types of rotational oil pumps that are available in the art or are novel can be also used in the embodiment of the present invention without limiting the scope of the present invention. An optional oil pump is depicted in Figure 5.

Reference is now made to Figure 5 illustrating an oil pump that can be utilized in a CVT in accordance with another preferred embodiment of the present invention. Oil pump 200 comprises an outer rotor 202 and an inner rotor 204. Peripheral ridges are provided in outer rotor 202 that correspond to peripheral protrusions of inner rotor 204. The rotation of the two elements pushes oil that is disposed between them 206. The drive shaft of the planet gear drives the oil pump in the CVT. The concept of the CVT is maintained unchanged.

Returning to Figure 2 illustrating the CVT. The lubricant (not shown in this Figure) is constantly flowing within oil canal 24 as long as control valve 26 is in an open state. When control valve 26 is fully open, planet carrier 22 rotates backward Iy, however is provided with a mechanism that does not allow it to rotate as will be shown herein after and ring gear 16 rotates while rotating output shaft 20. The transmission ratio in this state equals the number of teeth of sun gear 12 divided by the number of teeth in ring gear 16. In the example shown herein in Figure 1, the transmission ratio equals 21/108 which is 0.194- about 1 to 5 that correspond to first gearing position of a car, which is much more powered, and therefore, each 5 rotations of the car engine, which rotates input shaft 18, transmit 1 rotation to output shaft 20, which is rotating the car's wheels.

In the other extreme situation, control valve 26 is fully closed and it cause all gears in the apparatus to be locked together, the gears of the oil pump as well as the sun, planet and ring gears. The planet carrier rotates as one unit with ring gear 16 and therefore, the transmission ratio is 1 to 1 - for each rotation of the input shaft, the output shaft is rotating once in an equivalent manner. The transmission ratio is changed from the first extreme state to the second extreme state in a continuous manner that depends of the condition of the control valve and eventually, the gear ratio is determined by the condition of control valve 26 between those two extreme states.

The oil canal in the planet carrier can be provided with several oil pumps. The actuation of each one of the oil pumps is the same as explained herein before.

In case heavier machinery is to be used and in another aspect of the present invention, more than one oil pumps is needed to be used within the canal in the planet carrier. Reference is now made to Figure 4 illustrating a internal view of a planet carrier in accordance with another preferred embodiment of the present invention, provided with three oil pumps. Planet carrier 100 is provided with an oil canal 102 provided with three control valves 104 adapted to control the flow of oil within the canal. Oil canal 102 is provided with three oil pumps 106, each oil pump is provided with a pair of mating gears as previously explained. As mentioned herein before, this embodiment is intended to be used in cases there is a massive load, as an example, for actuating heavy machinery and big vehicles. The use of three oil pumps is beneficial since it deploys the oil pressure forces that are employed on the pumps in an unequal manner in order to reduce the force each pump tolerates. In each one of pumps 106, one gear of the pair is actuated by the planet gear that is provided within the CVT enclosure as explained herein before in the case of the single pair and single oil pump.

In order to understand the concept of increasing the number of oil pumps, let's assume the planed CVT has to transmit a moment of 15 Kg/m. In case one oil pump is used (as shown in Figure 1-2), the force will be concentrated on this single pump. In order to avoid breakdown of the CVT, three possible solutions can be employed; the first is to increase the diameter of the oil pump, the second is to increase the width of the teeth and the third and the beneficiary possibility is to increase the number of the oil pumps while there is a possibility to decrease their diameter in the example of using three pumps.

It should be noted that the number of oil pumps is dependant on the diameter of the planet carrier. It should be noted that the actuating gear of the pair can be any one of the pair, the inner gear or the outer gear, wherein in the shown case, the driving gear is the outer gear of the pair.

It should be emphasized that the number of oil pumps has to be equal to the number of control valves in order to keep the oil pumps in a position to avoid breakdown due to significant moment such as 15 Kg/m. It should be also emphasized that the timing of closing or opening the control valves as well as their position has to be carefully planned to be adjusted to one another. Otherwise, one of the oil pumps can bear in a certain timing higher moments and experience a failure. Reference is now made to Figures 6A and 6B schematically illustrating a roller clutch working on the principle of a CVT in accordance with a preferred embodiment of the present invention, in driving and floating situations, respectively. First, when the neutral [N] position is presented, full separation between the wheels and the rotating shaft that is rotated by the engine occurs in the transmission of the present invention. Two situations of the CVT are shown in Figure 6 wherein planet carrier 22 is shown to be associating with a roller clutch or a wedge roller 31 that is placed in a slider 33 that is capable of moving forward towards planet carrier 22 (6A) and away from it (6B). Roller wedge 31 is resiliency connected to slider 33 by spring 32 that pushes roller wedge 31 as a default. When it slides to planet carrier 22, the situation that is shown in Figure 6A is present and slider 33 is forwarded toward planet carrier 22 and roller 31 acts as a wedge that stops the planet carrier from rotating anticlockwise. When the car's drive handle is positioned on drive [D], the planet carrier 22 can be rotated clockwise as shown by the arrow indicated by CZI sign that indicate the possibility of the carrier to rotate; however, roller wedge 31 is in such association with planet carrier 22 that the carrier is unable to rotate only when the car is in start moving situation. Shaft 20 (in Figure 1) is connected to the car's wheels with no dependency on whether the control valves are open or closed as mentioned herein before but the position of the control valves of the oil canal determines the gear and force the wheels to revolve. When the oil canal is fully open, the transmission is in the first gear state wherein with closure way of the oil canal, the transmission is transformed into higher gears.

When the wheels are stopped due to the driver, roller wedge 31 is moved backwardly by slider 33, Spring 32 is now released and roller 31 isn't touching planet carrier 22 - the situation that is shown in Figure 6B is presented - is near to neutral state. In this state, planet carrier 22 is continuously rotating in an anticlockwise direction (the arrow indicated by the sign 0. As mentioned herein before, in spite the neutral situation, the engine is associating with the transmission and the transmission is rotating also in this situation, therefore, this situation is indicated by [DN]. Reference is now made to Figures 7A and 7B illustrating a roller clutch working on the principle schematically shown in Figures 6A and 6B. Figures 7A1 and 7B1 are enlargements of a part of Figures 7A and 7B, respectively so as to distinguish between the different elements. Axle 336 is a fixed axle onto which a gear 335 is rotating. Dick 333 (schematically illustrated as the slider in Figure 6) is mounted on axle 336. The movement of disk 333 on axle 336 is limited by a keyway 337 and a corresponding key projection 336' that is provided in the axle. For a Drive state [D], disc 333 is moved in clockwise direction as shown in Figure 7A1 and is moved anticlockwise to the position shown in Figure 7B1 in order to establish the state explained herein before DN - the floating state. The slider or disc 333 movements between the states is controlled using a control unit wherein by default, disc 333 is positioned in Drive state when gear handle positioned in [D] state that is shown in Figure 7A1. When the control unit is receiving an indication that the car is reducing speed close to zero speed, the control unit will force to move the disc 333 to move anticlockwise to the Neutral floating state as shown in Fig.7B1. Gear 335 in any case is associated with an external gear 334 mounted on planet carrier 22 so as to control the movements of the CVT that is enclosed within.

The state of roller 31 and spring 32 in slider 33 that is shown in Figure 6 and disc 333 are also shown in the application in Figures 7A and 7B. In Figure 7B1 , wedge rollers 31 are shown to be in a loose state within recess 338 so as to enable gear 335 to move without limitation. In Figure 7A1 , wedge roller 31 is stressed within recess 338 so as to press onto gear 335 and preventing its movement clockwise. As a consequence, planet carrier 22 is not rotating anticlockwise.

It should be clear that the description of the embodiments and attached Figures set forth in this specification serves only for a better understanding of the invention, without limiting its scope as covered by the following Claims.

It should be also clear that a person skilled in the art, after reading the present specification can make adjustments or amendments to the attached Figures and above described embodiments that would still be covered by the following Claims.

Claims

C L A I M S

1. A continuously variable transmission comprising a sun gear connected to an input shaft; a ring gear fixedly connected to an output shaft; at least one mating pair planet gear arranged between and engaged with said sun gear and said ring gear; a planet carrier, adjacent to and vertically enclosing said ring gear and said sun gear through which said input shaft passes, is provided with a canal; at least one control valve adapted to control flow of lubricant within said canal; at least one oil pump provided in said canal and engaged with said at least one planet gear that is capable of rotating together with said planet gear so as to allow flow of the lubricant within said canal.

2. The continuously variable transmission as claimed in Claim 1 , wherein one mating pair of planet gear is provided.

3. The continuously variable transmission as claimed in Claim 1 , wherein said at least one oil pump is a pair of mating gears.

4. The continuously variable transmission as claimed in Claim 2 or 3, wherein a joined shaft is connecting one of said pair of planet gears to one of said pair of mating gears.

5. The continuous variable transmission as claimed in Claim 1 , wherein said canal is circular.

6. The continuous variable transmission as claimed in Claim 1 , wherein the number of control valves equals the number of oil pumps.

7. The continuously variable transmission as claimed in Claim 1 , wherein three control valves are associating with three oil pumps.

8. The continuously variable transmission as claimed in Claim 1 , wherein said at least one oil pumps comprises an outer rotor provided with peripheral ridges and an inner rotor provided with corresponding peripheral protrusions and wherein the rotation of the inner rotor and the outer rotor pushes oil that is disposed between them.

9. The continuous variable transmission as claimed in Claim 1 , wherein said input shaft is rotated by a power source.

10. The continuous variable transmission as claimed in Claim 1 , wherein said sun gear is provided with a bore that is in connection with said input shaft.

11. The continuous variable transmission as claimed in Claim 1 , wherein said at least one control valve is operated by means selected from a group of mechanical, electrical, hydraulic, or pneumatic mechanism, etc.

12. The continuous variable transmission as claimed in Claim 1 , wherein when said at least one control valve is fully closed and oil is not flowing in said canal, said sun gear, said planet gear, said ring gear and said oil pump are fixed together as a unit with said planet carrier causing the continuous variable transmission to rotate together so as to establish a transmission gear ratio of 1 to 1.

13. The continuous variable transmission as claimed in Claim 1 , wherein the continuous variable transmission is associated with a clutch roller.

14. The continuous variable transmission as claimed in Claim 1 , further associated with a slider provided with a movable wedge roller capable of associating with said planet carrier and stopping said planet carrier from rotation.

15. The continuous variable transmission as claimed in Claim 14, wherein said wedge roller stops said planet carrier by friction.

16. The continuous variable transmission as claimed in Claim 14, wherein said slider is a disc mounted onto a fixed axle wherein said disc is capable of moving in a limited angular movement between a first position and a second position onto said fixed axle and wherein in the first position said wedge roller is loose and in the second position said wedge roller is pressing a gear that associates with an external ring gearwheel and force said planet carrier to stop its rotation backward.

17. The continuous variable transmission as claimed in Claim 16, wherein said axle is provided with a key projection and said disc is provided with a corresponding keyway that is limited within said key projection to allow said first position and said second position.

18. The continuous variable transmission as claimed in Claim 17 wherein said wedge roller is provided within a recess between a gearwheel that is associated with said planet carrier and said disc.

19. A continuously variable transmission substantially as described in the above specification, attached Figures and appending Claims.